Phase behavior and mechanical properties of blends of cellulose propionateand an alternating propene-carbon monoxide copolymer

Cellulose propionate (CP) and plasticized cellulose propionate (CP16) were blended, both in solution and by extrusion, with high molecular weight alte rnating propene-carbon monoxide copolymers (P-CO). Tensile testing was perf ormed on injection molded blends with a P-CO content of up to 50 wt.-%. The phase behavior was investigated by means of differential scanning calorime try and electron microscopy. The blends are miscible at compositions up to about 10 wt.-% P-CO. P-CO lowers the melt viscosity of both CP and CP16 and acts as a polymeric plasticizer. Higher amounts of P-CO result in phase se paration with domains of P-CO-rich material in the dispersed phase and a co ntinuous CP/CP16-rich phase with a T-g even higher than that of pure CP. In this state toughness decreases slightly with increasing P-CO content, whil e modulus and yield stress increase. After transition into the bicontinuous phase, occurring at a P-CO-content of around 25 wt.-%, toughness and elong ation at break increase significantly, while modulus and yield stress decre ase.